1. Field of the Invention
The present invention relates to improvements in cylindrical lock arrangements. The invention also relates to improvements in permutation lock arrangements.
Some of the uses of such cylindrical lock arrangements provide privacy lock-out systems. With a cylindrical lock arrangement, this can be provided by a mechanism which is activated by a push-button on the inside door knob as will be further described below. The present application is partially directed at novel lock-out systems.
2. Description of Prior Art
With permutation lock arrangements, of the type as described for example in U.S. Pat. No. 3,040,536, Rosenhagen, June 26, 1962, the shaft of the outside door knob is connected to the shaft of the permutation lock chamber. The shaft of the chamber will rotate, thereby permitting rotation of the outside door knob, only when the correct combination of the permutation lock has been punched in. Often, when the incorrect combination is inserted, so that the knob will not rotate, the user will apply excess force to the outside door knob to force the chamber shaft to rotate. This can cause damage to the chamber. It would therefore be desirable to provide means for permitting the outside door knob to rotate, under such conditions, without transmitting the rotating force to the chamber shaft.
With permutation locks, it becomes necessary, from time to time, to change the combination. It would therefore be desirable to provide a cover which is easily removable by an adult, but which would present difficulty for a child to remove.